Democratic 2020 contenders face a common problem

It may still be more than three years until the next presidential election, but, as recent campaign cycles have shown, that’s far from a long time when it comes to the battle for the White House. In their efforts to limit President Donald Trump to no more than one term then, it will be a concern to Democrats that most of their prospective challengers for 2020 face one common, significant problem: Most Americans don’t know who they are.